diff --git a/src/backend/src/filesystem/batch/commands.js b/src/backend/src/filesystem/batch/commands.js
index 782541d2f..4ebe6cf60 100644
--- a/src/backend/src/filesystem/batch/commands.js
+++ b/src/backend/src/filesystem/batch/commands.js
@@ -26,6 +26,7 @@ const { OperationFrame } = require('../../services/OperationTraceService');
 const { HLMkShortcut } = require('../hl_operations/hl_mkshortcut');
 const { HLMkLink } = require('../hl_operations/hl_mklink');
 const { HLRemove } = require('../hl_operations/hl_remove');
+const { safeHasOwnProperty } = require('../../util/safety');
 
 class BatchCommand extends AdvancedBase {
     static FEATURES = [
@@ -36,7 +37,7 @@ class BatchCommand extends AdvancedBase {
         let x = Context.get();
         const operationTraceSvc = x.get('services').get('operationTrace');
         const frame = await operationTraceSvc.add_frame(`batch:${ this.name}`);
-        if ( parameters.hasOwnProperty('item_upload_id') ) {
+        if ( safeHasOwnProperty(parameters, 'item_upload_id') ) {
             frame.attr('gui_metadata', {
                 ...(frame.get_attr('gui_metadata') || {}),
                 item_upload_id: parameters.item_upload_id,
@@ -149,6 +150,8 @@ class WriteCommand extends BatchCommand {
             operation_id: parameters.operation_id,
             item_upload_id: parameters.item_upload_id,
             app_id: app ? app.id : null,
+
+            thumbnail: parameters.thumbnail,
         });
 
         this.provideValue('result', response);
diff --git a/src/backend/src/filesystem/hl_operations/hl_write.js b/src/backend/src/filesystem/hl_operations/hl_write.js
index 589538a66..c2adefece 100644
--- a/src/backend/src/filesystem/hl_operations/hl_write.js
+++ b/src/backend/src/filesystem/hl_operations/hl_write.js
@@ -111,6 +111,9 @@ class HLWrite extends HLFilesystemOperation {
         create_missing_parents: new FlagParam('create_missing_parents', { optional: true }),
         user: new UserParam(),
 
+        // client-provided thumbnail as a base64 string
+        thumbnail: new StringParam('thumbnail', { optional: true }),
+
         // file: multer.File
     };
 
@@ -300,12 +303,14 @@ class HLWrite extends HLFilesystemOperation {
         let thumbnail_promise = new TeePromise();
         if ( await parent.isAppDataDirectory() || values.no_thumbnail ) {
             thumbnail_promise.resolve(undefined);
+        } else if ( values.thumbnail ) {
+            // Use the thumbnail provided by the client (base64 string)
+            thumbnail_promise.resolve(values.thumbnail);
         } else {
             (async () => {
                 const reason = await (async () => {
                     const { mime } = this.modules;
                     const thumbnails = context.get('services').get('thumbnails');
-                    if ( values.thumbnail ) return 'already thumbnail';
 
                     const content_type = mime.contentType(target_name);
                     this.log.debug('CONTENT TYPE', content_type);
diff --git a/src/backend/src/routers/filesystem_api/batch/all.js b/src/backend/src/routers/filesystem_api/batch/all.js
index d39c8e521..1c0a6388a 100644
--- a/src/backend/src/routers/filesystem_api/batch/all.js
+++ b/src/backend/src/routers/filesystem_api/batch/all.js
@@ -18,7 +18,6 @@
  */
 const APIError = require('../../../api/APIError');
 const eggspress = require('../../../api/eggspress');
-const config = require('../../../config');
 const { Context } = require('../../../util/context');
 const Busboy = require('busboy');
 const { BatchExecutor } = require('../../../filesystem/batch/BatchExecutor');
@@ -227,6 +226,11 @@ module.exports = eggspress('/batch', {
 
         const op_spec = pending_operations.shift();
 
+        // Copy thumbnail from fileinfo to the file object if provided
+        if ( file.thumbnail ) {
+            op_spec.thumbnail = file.thumbnail;
+        }
+
         // index in response_promises is first null value
         const index = response_promises.findIndex(p => p === null);
         response_promises[index] = batch_exe.exec_op(req, op_spec, file);
diff --git a/src/backend/src/routers/filesystem_api/write.js b/src/backend/src/routers/filesystem_api/write.js
index c5975430d..44824fdc7 100644
--- a/src/backend/src/routers/filesystem_api/write.js
+++ b/src/backend/src/routers/filesystem_api/write.js
@@ -44,7 +44,7 @@ module.exports = eggspress(['/up', '/write'], {
     //     fsNode: new FSNodeParam('path'),
     //     target: new FSNodeParam('shortcut_to', { optional: true }),
     // }
-}, async (req, res, next) => {
+}, async (req, res, _next) => {
     // Note: parameters moved here because the parameter
     // middleware won't work while using busboy
     const parameters = {
@@ -63,7 +63,7 @@ module.exports = eggspress(['/up', '/write'], {
 
     const x = Context.get();
     let frame;
-    const frame_meta_ready = async () => {
+    async () => {
         const operationTraceSvc = x.get('services').get('operationTrace');
         frame = (await operationTraceSvc.add_frame('api:/write'))
             .attr('gui_metadata', {
@@ -183,6 +183,8 @@ module.exports = eggspress(['/up', '/write'], {
         file: uploaded_file,
 
         app_id: app ? app.id : null,
+
+        thumbnail: req.body.thumbnail,
     });
 
     if ( frame ) frame.done();